Dynamic Hyperinflation and Mechanical Ventilation

Airflow resistance during exhalation is increased, making it harder to breathe out.

Constriction of the airways, making it difficult to exhale.

A narrowed or bent breathing tube makes it difficult to exhale.

Thick mucus buildup in the airways obstructs airflow during exhalation.

The lung's ability to spring back after inspiration is reduced, causing air to be trapped in the lungs.

A situation where the lungs become overly inflated due to the inability to fully exhale, caused by high PEEP levels.

The pressure applied to the airways at the end of expiration to keep them open.

The increased volume of air inside the chest cavity due to excessive inflation.

The increased pressure inside the chest cavity due to increased intrathoracic volume.

Injury to the lungs caused by excessive pressure.

Reduced blood flow back to the heart, leading to decreased blood volume.

Difficulty breathing due to increased intrathoracic pressure, making it harder to take a breath.

Treating reversible factors such as bronchospasm, secretions, and expiratory devices can improve lung function and ventilator management.

Prolonging expiratory time, achieved by decreasing the inspiratory-to-expiratory (I:E) ratio, respiratory rate (RR), or increasing inspiratory flow, helps prevent air trapping and improve gas exchange.

Decreasing tidal volume reduces lung stress and improves ventilation-perfusion matching, especially in patients with lung injury.

PEEPi (expiratory hold) measures the pressure required to prevent alveolar collapse at the end of exhalation.

Setting exogenous PEEP to approximately two-thirds of PEEPi can improve gas distribution and reduce inspiratory effort, but ZEEP (zero PEEP) may also be considered.

A method used to measure the pressure remaining in the lungs at the end of a breath, even after the patient has exhaled.

The pressure measured during the expiratory hold maneuver, representing the pressure remaining inside the lungs after exhalation.

During the maneuver, the patient's airway is temporarily blocked (occluded) for a short time (3-5 seconds) to stop airflow. This allows the pressure inside the lungs to reach the same pressure as the pressure in the airways.

The pressure in the lungs is allowed to equalize with the pressure in the airways.

The expiratory hold maneuver is performed at the end of a normal exhalation, allowing the pressure in the lungs to stabilize before measurement.

The pressure in the lungs at the end of a normal exhale.

The pressure in the lungs when the lungs are full.

The amount of air a person breathes in and out.

The rate at which air moves in and out of the lungs.

A way to measure airflow during breathing, showing how air flow changes over time.

Shows the pressure changes in the lungs over time.

A visual representation of how breathing volume changes over time.

A method to assess dynamic hyperinflation by observing the expiratory flow curve and seeing if it reaches baseline.

A method to assess dynamic hyperinflation by disconnecting the breathing tube and observing the patient's exhalation.

Intrinsic PEEP is the pressure remaining in the lungs at the end of exhalation, regardless of external ventilator settings. It occurs due to internal obstructions like airway narrowing or thick secretions slowing airflow out of the lungs.

The presence of iPEEP can be a sign of airway obstruction or decreased lung elasticity, and requires adjustment of ventilator settings to prevent complications like air trapping or lung injury.

Extrinsic PEEP is the pressure applied by the ventilator at the end of exhalation to keep the airways open. It's controlled by the machine.

iPEEP results from factors within the patient's respiratory system that hinder airflow out of the lungs, while Extrinsic PEEP is a controlled pressure applied by the ventilator.

Understanding both iPEEP and Extrinsic PEEP is crucial for effective ventilator management. Clinicians need to differentiate these pressures and adjust ventilator settings appropriately.

Intrinsic PEEP (iPEEP) is a positive end-expiratory pressure (PEEP) generated within the respiratory system. It occurs passively during mechanical ventilation as a result of factors impeding expiratory flow.

iPEEP can be caused by various factors like airway obstruction (bronchospasm, secretions), air trapping (high respiratory rate, delayed exhalation), high inspiratory pressures, decreased lung compliance (pulmonary edema), and secretions.

iPEEP increases the work of breathing because it requires more pressure to overcome during inspiration. It also reduces tidal volume as complete expiration is impeded, potentially reducing the volume of air inhaled.

High iPEEP can also lead to reduced lung compliance (stiffness), increased risk of barotrauma (lung injury from pressure), impaired gas exchange and oxygenation, negative cardiovascular effects (decreased venous return and cardiac output), and lung injury.

Addressing the underlying cause is key to managing iPEEP. This may involve treating bronchospasm, clearing secretions, reducing inspiratory pressures, and addressing lung compliance issues.

Prolonging expiratory time can improve exhale and reduce air trapping. This can be achieved by decreasing the inspiratory-to-expiratory (I:E) ratio, respiratory rate (RR), or increasing inspiratory flow.

Decreasing tidal volume reduces lung stress and improves ventilation-perfusion matching, especially in patients with lung injury.

PEEPi (expiratory hold) is a measurement of the pressure needed to prevent alveolar collapse at the end of exhalation. This helps determine if any iPEEP is present and guides PEEP setting.

iPEEP is important to address because it can be a sign of airway obstruction or decreased lung elasticity, and it can lead to complications like air trapping or lung injury. Knowing iPEEP can help clinicians adjust ventilator settings to improve lung function.

Adjusting ventilator settings like inspiratory flow rate, inspiratory time, or tidal volume can help to reduce iPEEP. Proper patient positioning, reducing sedation, and considering non-invasive ventilation can also be effective.

Prolonging expiratory time can help to improve exhale and reduce air trapping. This can be achieved by decreasing the inspiratory-to-expiratory (I:E) ratio, respiratory rate (RR), or increasing inspiratory flow.

iPEEP can make it much harder for patients to breathe because they have to push harder to get air in. It can also lead to air trapping, making the lungs stiff and more prone to injury.

The best way to deal with iPEEP is to find the reason it's happening. Are the airways narrowed? Are there thick secretions? Once the cause is known, we can treat it and make it easier for the patient to breathe.

Changing the settings on a ventilator can help reduce iPEEP. We can increase the flow rate to speed up inhalation, or extend the exhale time by decreasing the breathing rate. This gives the lungs more time to let air out properly.

Intrinsic PEEP is different from extrinsic PEEP, which is set by the ventilator. Extrinsic PEEP is a pressure applied at the end of exhalation to keep the airways open. But intrinsic PEEP is caused by factors within the patient themselves.